I'm resident in Prague, working for the french embassy, so I can give a few hints.
Keep your passport and travel documents in your hotel secure lockout (coffre-fort, in french). Be sure to keep your important belongings (money, credit cards) in an inner pocket of your vest/avoid keeping things in your external pockets and in jeans pockets. Pickpockets are generally dark-skinned and shifty looking. Most of them are found on tram line N°22 which goes up to the castle. If you want to visit the castle, go by foot, do'nt take the tram. I take the tram 22 often and never had a single problem. Places to avoid include the train stations in Prague (Hlavni Nadrazi, Masarykovo Nadrazi). IMPORTANT RULE : !!!NEVER!!! pick up a taxi who is stopped. Call one who's driving on the street (yellow lit = free) or call one through AAA Taxi (phone number : 14014)
Be aware that sometimes pickpockets operate in couple and that one might be distracting you (asking questions, asking for their way) while the other one will be doing your pockets as you try to help. Some others in public transportation will sometimes fake a dispute to divert attention, while a third one will be checking for people's pockets. It's very rare, though. In the center of the town, near Staromestké Namesti (old square) you might find women asking you if you want to have sex, and if you look young enough some shiftly looking dudes might propose you marijuana or other kind of crap like this. Just walk your way and ignore them. 🙂
The metro is very clean and problems are pretty rare. Also it's rare to see people fighting on the street, the czech people are generally very quiet, though a bit inexpressive/cold according to my own opinion after living for nearly 5 years in the country.
Honestly, thieving here is marginal, though everyday people get fooled, and not only tourists. It's just a matter of common sense while on the street.
Other advices : restaurants located in the immediate vicinity of touristic places ARE real thieves and will charge you insane amounts of money for mediocre quality food. Don't be afraid to walk a couple streets nearby to find a nice restaurant. Regarding tips, generally it's 10% of the bill price, if they were nice.
Weather got quite cold here since the beginning of the week. Now it really feels like autumn.
Regarding shooting, you won't ever get any problems. People are used to a massive flow of tourists, and i've been shooting even out of the touristic areas with discrete and unobtrusive cameras such as a Pentacon Six fitted with the tiny Carl Zeiss Sonnar 180mm f/2.8, and with all sorts of cameras in any situations. Never had a single problem. Same in Paris. Just enjoy your holidays and drop me a pm if you want to meet for a beer 🙂
Cheers,
Max
